Perkinsoceras has what have been interpreted as tubules that form where the endocones impinge on the process, a feature also interpreted in Williamsoceras, Cacheoceras and the distinctly unique Allotrioceras Perkinsoceras differs from the generally similar Chazyoceras by its ventral process -absent in the latter, and by its more bulbous nanno type apex.
Williamsoceras and Cacheoceras differ in having a straight cameroceras type apex without the expanded siphuncle.
Two species of Perkinsoceras have been described, both early Middle Ordovician (Chazyan) in age, both from Vermont.
P inflatum comes from the Crown Point Limestone, 1/2 mile south of Ferrisburg Vt.
The holotype is in the Paleontology collection of the New Mexico Museum of Natural History and Science.